Actually I had in mind device, which will affect/jam sharing sensors ability.

With ECM/Stealth affecting those who can see You in their range, but extra tool/device making visibility in affected area more difficult for those who see You through shared sensors.

So let say:
A - visible target
B - someone who's using his perception or ship/vehicle scanner and can see/spot You - You're in his vision range.
C,D,E - others, who can see A, thanks to shared sensors from B

B still can see A, if A's stealth / ECM is smaller (or skill check failed) than B's perception/scanners

After activating jamming device by A or someone in the area (skill check, delay, whatever) - C,D,E may fail to notice A - or have a part of their shared visibility blacked.